Air conditioning control circuit



July 7, 1936.

J. s, BAKER AIR CONDITIONING CONTROL CIRCUIT Filed Sept. 20, 1953 I Yr x ww mm "N Q Q I m Patented July 1, 1936 John s. Baker, Chicago, 111., assignor to Cook Electric Company, Chicago, 111., a corporation of Illinois Application September 20; 1933, Serial No. 690,216

14 Claims. (01. 236-44)" This invention relates to improvements in airconditioning systems, and, more particularly. to forced air circulating systems equipped with washers or with washers and filters. Heretofore, it has been customary in such installations to provide a washer consisting of suitable spray heads which are fed from a suitable water pipe line. In this line is generally placed a magnetic-valve controlled by a humidistat which is so arranged that when the air is sufliciently dry the magnetic valve is caused to open, permitting water to flow to the spray.

heads. When suflicient moisture has been added to the air, the humidistat circuit opens, thus closing the water valve and shutting off the spray. Generally, in a forced air system, these sprays are permitted to operate only at such time as the blower is operating. The result of this is that very frequently wh'enthe system is go first starting up, the blower andthe magnetic valve will both attempt tojoprate'; at the same time. The starting current talienfby the blower motor causes a very decided momentary decrease in line voltage. If only this decreased 25 line voltage is available for opening'the water valve, the valve is quite apt to stick because generally these valves are of the so-called impact type, and with decidedly reduced line voltage the initial impact relied on to open the valve is 30' lacking and the valve will fail to open but sets up a very annoying hum or chatter. A particular object of my invention is to provide a time delay between the starting of the motor and the opening of the valve, so that full line;

5 voltage will be restored and availablefor opening the valve.

Further, in such systems, it is quite common to arrange the sprays so that they will flush the air filters free from dirt. However, it has been 40; found that if the blower is running at the same time; the air forces the dirt against'the filter so tightly that the water is unable to flush it down and clear the filter. It therefore becomes desirable to operate the sprays fora short time 45. when the blower is not running, so that the-accumulated dirt can be washed away. I advantageously utilize the same time delay element to keep the water valve open for a short while after the motor stops.

50 In the drawing, I have shown the complete circuit for an air-conditioning system of the type Just described. In this drawing, I is a conventional room thermostat arranged to'close contacts 3 and 2 when the temperature-falls and to close contacts 3 and 4 when the temperature rises. 5 is' a manually operated switch arrangedto have contacts 6 and 1 close and cbntaets 8 and 9 open when the system is being used for heating, and to have contacts 3 and I open and contacts 8 and 9 close when the system 5 is being used for air-circulationin the summer time. I!) is a thermal switch or furnacestat, and is generally arranged with its actuating element in the bonnet of a warm air furnace. This switch is equipped with fan control contacts II and I2 10 7 so arranged that below a pre-determined temperature these contacts are open and above a predetermined temperature they are closed. It is also equipped with draft control contacts I4 and I5 so arranged that above-a predetermined temperature these contacts are open and below a predetermined temperature these contacts are closed; It is also equipped with an emergency contact l3 so arranged that above a predetermined temperature contacts 13 and M are closed. a

A draft controller I6 is so arranged that when its actuating coil I1 is energized it opens the draft and closes the check, and, when de-energized, it closes the draft and opens the check. A standardtransformer I8 is equipped with primary winding 20 and secondary-winding l9 for feeding low voltage to the control circuit. 2| is any type of suitable relay arranged when en-' ergized to close contacts 22 and 23 and open contacts 4| and 42, and when deenergized' to open contacts .22 and 23 and close contacts 4| and 42. A manually operated switch 24 is so arranged that contact 25 may be connected either to contact 21 or contact 26, or left dis- 5 connected entirely. 28 is any type of commercial humidistat. 29 is an electrically operated water valve. 30 is a transformerqsimilar to transformer I8 and is equipped with a primary coil 3| and a secondary coil 32. 33 is any commercial, air blower for forcing the air through the ducts of the air-conditioning system, including the screen or humidifier 33'. 34 is an autotransformer delivering low-voltage across terminals 35 and 33. 31 is a warp switch of con-.

ventional design; so arranged that when heating coil 38 is energized a time delay is introduced before contacts 39 and I0 close. Similarly, when coil 38 is deenerglzed, a time delay is introduced before contacts 39 and 49 open. '50

The operation of the system will now be dew; scribed: When set for winter operation, switch 5 will have contacts 5 and l'closed and contacts 8 and 9 open. When room thermostat I calls for heat, contacts 2 and 3 will be closed, estabauto-transformer 34 causes low voltage current lishing the following circuit; contact 2, wire a, ary :2, wire a, wire 12, contact 42, contact an,

switch 6, wire 44, contact l4, contact l3, wire 43, damper control coil wire 46, wire 41,

transformer secondary l3, wire 43, damper control l6, wire 43, wire 63 and contact 3. The closing of this circuit energizes damper control coil l1, causing it to open the draft and close the check on the furnace. This results in accelerating the fire and increasing the heat in the bonnet of the furnace. As soon as the temperature in the bonnet of the furnace has reached the predetermined point, contacts II and I2 are closed,

completing the following circuit: Transformer secondary I3, wire 41, wire 6|, relay 2|, wire 62, wire 33, contact contact l2, wire 64, wire 44, switch 6, wire 43, contact 2, contact 3, wire 63, wire 43, damper control l6, wire 43; to transformer secondary iii. The closing of this circuit energizes relay 2|, which results in closing relay contacts 22 and 23 and opening relay contacts and 42. 1 3

The closing of relay contacts 22 and 23 starts the blower motor 33 throughthe following circuit: From the line througliwire 66, wire 56, contact 22, contact 23, wire 61, wire 63, blower motor 33, wire 53, wire 60 and back into the line. Blower 33 immediately starts, and, in addition, the circuit to auto-transformer 34 is energized through the following circuit: wire 66, wire 66, contact 22, contact 23, wire 61, wire 62, autotransformer 34, wire 6|, wire 63. Energizing to flow in the secondary circuit, which consists of wire 63, coil 33, and wire 64. The heating of coil 33 causesthe warping member 33 to move towards contact 43. After a suitable lapse of time it establishes contact, which results in closing the following circuit: From the line through wire 63, wire 6|, wire 63', contact 33, contacts 40, wire 65, transformer primary 3|, wire 66, wire 56 to the line. This energizestransformerfl, and if humidistat 23 is calling for more moisture in the air, and switch 24 set so that contacts 26 and 26 are closed,. water valve 23 is opened through the following circuit: transformer secondary 32, wire 63, contact 26, contact. 26 wire 63, humidistat 23, wire Ill, contact 21, wire ll, water valve 23, wire 61, to transformer secondary32. i

In the cycleof operation just described blower motor 33 always starts a predetermined length of time before water valve 23 opens. This permits blower motor 33 to attain full speed and allows full line voltage conditions'to be restored in the circuit before water valve 23 opens. This is because if water valve 23 is of the magnetic impact type; it is quite likely to fail to open under reduced voltage conditions. The

spraying or .ilushingdown of the filter 33' during periods when blower motor 33 is not operating tacts 4| and 42. Opening contacts 22 and.

immediately stops the operation of blower 33, but transformer 33 is still energized, due to the delayofwarpswitch3lopeningitscontacts33' and 4..

Since transformer 33 is energized, watervalve 23 remains open the instant relay 2| is deenergiaed because of the establishment of the following circuit: water valve ".transformer secondwire 13, wire Ii, to water valve 23. Accordingly, the water valve 23 will remain open and the sprays will operate to flush the filter 33 during the time that warp switch 31 is cooling and until 5 it has cooled sufficiently to open contacts 33 and 40. This flushing action occurs at the end of each operating period, regardless of the position of switch 24 and of whether humidistat 23 is in the open or closed position.

For air circulation in the summertime, switch, I is thrown to close contacts 3 and 3 and open contacts 6 and I. Then, whenever the temperature of the room rises sufllciently high to cause contacts 3-and 4 of room thermostat; I to close, the blower operates through the following circuit: contact 4, wire 14, contact 3, contact 3, wire 16, wire 52, relay! 2|, wire 5|, wire 41, transformer secondary l3, wire 43, damper control i6, wire 43, wire '63, and to contact 3. Energizing relay 2| starts'the blower, as previously described, and at the end of each period of blower operation, the air-filters will be flushed down, the same as in wintertime operation.

It is not essential that the .inventionbroadly 25 be associated with the temperature control of a heating system. A simple circuit arrangement may be had including only the blower motor 33, water valve 23, and humidktat 23, with a control element similar to the room thermostat l. Essentially. the time delay element 31, whatever form it maytake, and I contemplate the use of any type of construction for it, operates advantageously to initiate operation of water valve 23 after blower motor 33 has started and the line 3 voltage is again normal Time delay element 31 further operates advantageously to cause continued operation of water valve 23 after the blower motor 33 has stopped, in order to assure washing of fllter 33'.

Without further ehboration, the foregoing will so fullv explain the gist of my invention that others may, by applying current knowledge, readily adapt the same forms under varying conditions of service, without eliminating oer- 45 tain features, which may properly be said to constitute the essential items of novelty involved, which'items are intended to be defined and secured to me by the following claims.

I claim:

1. In an airconditioning system, the combination of a motor driven air blower, a humidifier, an electrically operated valve controlling the flow of moisture to said humidifier. a control circuitforsaidparts,andaflme-delayelement in said control circuit for delaying the opening ofsaidvalveuntilaftersaidmotordrivenair' blower is in operation.

2. In an mtem. the combination of a motor-driven air blower, a humidifier, 00

ated valve for controlling said liquid s control circuit includima source ofelectric potential, a regulator for said control circuit renderingsaidairbloweroperativaandmeans for delaying the operation of said electrically operatedvalveuntilslidairblowerhasbcenfl rendered operative and the line potential ha been restored.

4. In an air conditioning system, the combination of an air blower, a humidifier and a source of liquid supply therefor, a valve for controlling said liquid supply, a regulator for rendering said i said air bloweris stopped by said regulator irrespective of the condition of said humidistat.

5. In an air conditioning system, the combination of an air blower, a humidifier and a source of liquid supply therefor, a valve for controlling said liquid supply, a control circuit for said air blower, an auxiliary control circuit having means therein for operating said valve, and connections between said control circuit and said auxiliary control circuit for closing said auxiliary circuit upon the opening of said control circuit.

6. In an air conditioning system, the combination of an air blower, a humidifier and a source of liquid supply therefor, a valve for controlling said liquid supply, a control circuit for said air blower, an auxiliary control circuit having means therein for operating said valve, a humidistat for controlling said auxiliary circuit, and connections between said control circuit and said auxiliary circuit for closing said auxiliary circuit, irrespective of the condition of said humidistat, upon the opening of said control circuit.

7. In an air conditioning system, the combination of an air blower, a humidifier and a'source of liquid supply therefor, a valve for controlling said liquid supply, a control circuit for said air blower, an auxiliary control circuit having means therein for operating said valve, a humidistat for controlling said auxiliary circuit, and an automatic circuit-making-and-breaking device between said control circuit and said auxiliary circuit for closing said auxiliary circuit when said control circuit is open whereby to operate said valve means irrespective of the condition of said humidistat.

8. In an air conditioning system, the combination of an air blower, a humidifier and a source of liquid supply therefor, a valve for controlling said liquid supply, a control circuit for said.

air blower, an auxiliarycontrol circuit having means therein for operating said valve, and

circuit is open, and a time delay circuit makingand-breaking element between said control circuit and said auxiliary circuit for continuing the flow of current through said auxiliary circuit for a predetermined period of time after said control circuit is opened.

10. In an air conditioning system, the combination of an air blower, a humidifier and a source of liquid supply therefor, a valve for controlling said liquid supply, a control circuit for said air blower, an auxiliary control circuit having means therein for operating said valve, and a time-delay circuit-making-and-breaking element between said control circuit and said auxiliary circuit for efiecting a time-delay in the operation; of said auxiliary circuit after the operation of said control circuit.

11. In an air conditioning system, the combination of an air blower, a humidifier and a source of liquid supply therefor, a valve for controlling said liquid supply, a control circuit for said air blower, an auxiliary control circuit having means therein for operating said valve, a time-delay circuit-making-and-breaking element between said control circuit and said auxiliary circuit for effecting a time-delay in the operation of said auxiliary circuit after the operation of said control circuit; and means for closing said auxiliary circuit when the operation of said air blower is stopped.

12. In an airconditioning system, the combination of an air blower, a humidifier and a source of liquid supply therefor, a valve for controlling said liquid supply, a control circuit for said airblower, an auxiliary control circuit having means there-in for operating said valve, a timedelay circuit-making-and-breaking element between said control circuit and said auxiliary circuit for effecting a time-delay in the operation of said auxiliary circuit after the operation of said control circuit, and a relay for closing said auxiliary circuit when said control circuit is opened.

13. In an air conditioning system, thecombination of an air blower, a humidifier and a source of liquid supply therefor, a valve for controlling said liquid supply, a control circuit for said air blower, an auxiliary control circuit having means therein for operating said valve, and a thermally operated element controlled by the heat efiects of the current flow through said control circuit for controlling the flow of current through said auxiliary circuit, said thermally operated element effecting a time-delay with respect to the current flow in said control circuit, in controlling the flow of current in said auxiliary circuit.

14. In an air conditioning system, the combination of an air blower, a humidifier, and a source of liquid supply therefor, a control circuit for said air blower, a valve for controlling said liquid supply, an auxiliary control circuit for said valve, and a thermally operable element controlled by the current flowing through said blower control circuit for controlling the flow of current through said auxiliary control circuit.

. JOHN S. BAKER. 

